Impact of palmitic acid coating on the water uptake and loss of ammonium sulfate particles

International audienceWhile water insoluble organics are prevalent in the atmosphere, it is not clear how the presence of such species alters the chemical and physical properties of atmospheric aerosols. Here we use a combination of FTIR spectroscopy, Transmission Electron Microscopy (TEM) and Aerosol Mass Spectrometry (AMS) to characterize ammonium sulfate particles coated with palmitic acid. Coated aerosols were generated by atomizing pure ammonium sulfate, mixing the particles with a heated flow of nitrogen with palmitic acid vapor, and then flowing the mixture through an in-line oven to create internally mixed particles. The mixing state of the particles was probed using the AMS data and images from the TEM. Both of these probes suggest that the particles were internally mixed. Water uptake by the mixed particles was then probed at 273 K. It was found that for ammonium sulfate containing ~20 wt% palmitic acid the deliquescence relative humidity (DRH) was the same as for pure ammonium sulfate (80±3% RH). For particles with ~50 wt% palmitic acid however, the mixed particles began to take up water at relative humidities as low at 69% and continued to slowly take up water to 85% RH without fully deliquescing. In addition to studies of water uptake, water loss was also investigated. Here coatings of up to 50 wt% had no impact on the efflorescence relative humidity. These studies suggest that even if insoluble substances coat salt particles in the atmosphere, there may be relatively little effect on the resulting water uptake and loss

The Sword, April 1993

Volume 28, Issue 10, published April 13, 1993. This issue of The Sword is from the 1992-1993 academic year

The Sword, May 1975

Volume 10, Issue 7, published May 14, 1975. This issue of The Sword is from the 1974-1975 academic year

Oral History Project World War II Years, 1941-1946 - Elmer Andersen

Elmer L. Andersen was born on 17 June 1909 in Chicago, Illinois, one of four children. He grew up in Muskegon, Michigan, attending public schools and junior college, graduating in 1928. Andersen relocated to Minneapolis in 1928 and, after a year as a salesman, enrolled at the University of Minnesota; he graduated in 1931 with a degree in business administration. He was married in 1932 (wife Eleanor Johnson). In 1934 Andersen began working for H.B. Fuller Company in St. Paul, first in sales and by 1941 as president of the company. During the war years 1941-45 H.B. Fuller expanded its positions in the industrial adhesives industry, thanks in part to numerous government and military-related contracts; as president, Andersen was instrumental in the company’s growth and success. By 1945 the company was situated for a move into new markets, using contacts and profits from the war years. Andersen remained with H.B. Fuller as president and CEO until 1974, building it into a Fortune 500 company with a worldwide presence. Andersen was also involved in politics for many years, serving as a Minnesota state senator (1949-58) and as governor of Minnesota (1960-63). In addition, Andersen has donated time, energy, and financial resources to numerous causes, among them the Minnesota Historical Society and Voyageurs National Park. At the time of this interview (March 2003) Elmer Andersen lived in Arden Hills, Minnesota